I posted some time ago #243, what I found was engine braking spewed fuel out like when first starting bike. My fuel mileage dropped drastically, so I changed it back. What made a more significant difference was adjusting my TPS as was suggested by Invader in a previous thread. Like a different bike, I have driven at 2500 to 3000 RPM in 3RD gear, and it is very smooth.

How much of an adjustment did you give your main throttle sensor (TPS)? Is your main throttle sensor voltage output at WOT still withing spec?

How much of an adjustment did you give your main throttle sensor (TPS)? Is your main throttle sensor voltage output at WOT still withing spec?

Normally once I solve a problem I forget it, in this case it has been over two years, I have no problem keeping up with my son's 919 Honda, and I get much better gas mileage.

Since it isn't a problem, I really don't have the patience to look in the manual to find out were to measure and what readings I should get. However out of curiosity and for the others that participate on this forum, I would be willing to check this, if you could provide some direction.

Normally once I solve a problem I forget it, in this case it has been over two years, I have no problem keeping up with my son's 919 Honda, and I get much better gas mileage.

Since it isn't a problem, I really don't have the patience to look in the manual to find out were to measure and what readings I should get. However out of curiosity and for the others that participate on this forum, I would be willing to check this, if you could provide some direction.

It involves measuring main throttle voltage output at WOT, as directed in service manual.

I have had this thread bookmarked since first getting my Versys, and will be attempting the mod today, since I'll have the bike half-apart to change spark plugs and clean the air filter.

Can someone please confirm that the diagram below is the best option. I have seen talk of other methods, but they all seem to lead back to this setup. I looked on the french site as well, and this seemed to be the method used (as best I could tell, without translation).

It seems I need to couple the carb sync fittings together using hose and T connector, and also cut the original hose coming from the IAP (far left fitting if sitting on the bike), inserting a T connector, which the single end of the carb sync T connector inserts into. Sound right?

The problem is you do not want a unrestricted vacuum connection between throttle bodies. It would have been a lot simpler for Kawi to do this than implement the more complex sync connection between the two. The reason for this is when one cyl is drawing air it will lower the vacuum in the adjacent cyl with a vacuum pulse. This makes the mixture richer but reduces performance slightly. If Kawi did not care as much about performance they would have used a much cheaper single throttle body that would have equalized vacuum like this. The reason for the dual throttle bodies is so the drawing of one cyl does not effect the other, also the large air box helps with this too - the volume of the air box is several times the capacity of both cyl.

I would like to see someone dyno their bike before and after this mod.

Sorry twowheels, are you saying there is a problem with the way I just set it up (method in the linked post - which bypasses the left sync port)??? Or just filling me in on the how/what/why of what this mod does, or why it's better with it?

Either way, I appreciate the post. . I'm just trying to get a definitive answer to what the common consensus is for the best method.

Hi,
the guy that invented this mod at first time connected left and right body by a line.
That is mod 1 (I made on my V).
After he made an evolution that is the diagram that you posted.
Your diagram is definitively ok.

OK folks. While I really appreciate all the help this forum provides, this is one of those times that each post gets me more and more confused.

The very first post of this thread contains the mod, as explained by Invader. The diagram I posted above is an exact replica of that first post (photo #3). My plan was to do exactly as Invader and the diagram described.

But after reading 11 pages of posts in this thread, it seemed that there may have been a change of heart - a more simpler way of doing it. MoFlow confirmed this by linking HERE

So I just completed the mod as described in the photo (also by invader) in the link above, NOT like the diagram I posted. That "NEW" way of doing it doesn't tie the two bodies together, then link it into the IAP line with a second T connector. It simply puts a line between IAP port on the left body, and the sync port on the right body - and with a T connector - ties that to the stock IAP hose.

The way I understand it is:

Version #1: tie both bodies together with line and T connector. Splice T connector into IAP line (both ends of the IAP line remain where they are from factory. Tie both T connectors together with line.

Version #2: Tie IAP port (on left body) to right body with line and T connector. Tie stock IAP line into empty side of T connector. No cutting the IAP line (gray). Don't remove rubber cap from left body.

Sound right? I went with the Version #2, based on the latest post from MoFlow about it. Is there a reason I should go back to Version #1, which is the way Invader originally posted it???

I guess I have more posts to edit... Go with the best and most simple configuration #1, with a single 6" (15 cm) long 1/8 or 5/32" (3mm) ID vacuum hose on both TB vacuum ports. Leave the left outer IAP hose alone, and forget about using a T:

Thanks for weighing in here. For the benefit of anyone who may read this later - the photo above is yet a third option, at least since my posts. Do you think there is performance benefit to going with this last option (in your photo above)?

I have already reinstalled the tank etc, and currently have it as the #2 option in my previous post (which I believe was originally posted by you somewhere).

If there is an improvement - I'll take it apart again. But if it would only be a simpler option, then it's probably MORE simple for me to leave the tank/air box on at this point

Appreciate all the help folks. Maybe there should be a definitive sticky for this mod???

Just a comment: You don't have to remove the gas tank to do the mod as Invader has just shown with the last set of photos. I was able to hook up the single line between throttle bodies with a nice long pair of needle nose pliars. Lot faster than removing the tank.....